1. Field of the Invention
The present invention relates to a fluid compressor, and more particularly, to a compressor for compressing refrigerant gas in a refrigerating cycle, for example.
2. Description of the Related Art
Conventionally known are various compressors, including reciprocating compressors, rotary compressors, etc. In these compressors, however, the compression section and driving parts, such as a crankshaft for transmitting a rotatory force to the compression section, are complicated in construction, i.e. with many components being used in their construction. For higher compression efficiency, moreover, these conventional compressors should be provided with a check valve on the discharge side thereof. However, the difference in pressure between two opposite sides of the check valve is so great that gas is liable to leak from the valve. Thus, the compression efficiency cannot be high enough. In order to solve these problems, both dimensional and assembling accuracies of the individual parts or components must be improved, which entails an increase in manufacturing costs.
A screw pump is disclosed in U.S. Pat. No. 2,401,189. In this prior art pump, a columnar rotating body, which has a spiral groove on its outer peripheral surface, is disposed in a sleeve. A spiral blade is slidably fitted in the groove. As the rotating body is rotated, a fluid, confined between two adjacent turns of the blade in the space between the outer peripheral surface of the rotating body and the inner peripheral surface of the sleeve, is transported from one end of the sleeve to the other.
Thus, the screw pump serves only to transport the fluid, and is not adapted to compress it. During the transportation, the fluid can be sealed only if the outer peripheral surface of the blade is continually in contact with the inner peripheral surface of the sleeve. While the rotating body is rotating, however, the blade cannot easily slide smoothly in the groove, due to its susceptibility to deformation. It is difficult, therefore, to continually keep the outer peripheral surface of the blade intimately in contact with the inner peripheral surface of the sleeve. Thus, the fluid cannot be satisfactorily sealed. In consequence, the screw pump of this construction cannot produce any compression effect.